1. Field of the Invention
The invention relates generally to Location Finding technology for Wireless Local Area Network (WLAN) subscribers and, in particular, the invention relates to a method of providing location services for WLAN subscribers in a WLAN inter-working with a Third Generation (3G) network.
2. Related Technology
With the rise and development of WLAN technology, the main focus of current research is shifting to the interworking between WLANs and the global wireless mobile telecommunication systems like GSM, CDMA, WCDMA, TD-SCDMA, and CDMA2000. Among these systems, WCDMA and TD-SCDMA are standards for the Third Generation Partner Project (3GPP) while CDMA2000 is for the Third Generation Partner Project II (3GPP2).
The 3GPP standardization organization defines GERAN and UTRAN as the access network for GSM and UMTS, respectively, which can also be use for Location Services. A 3GPP network provides external LCS clients with the access of location services through the Gateway of Mobile Locating Center (GMLC). 3GPP defines a network architecture of the LCS. The network architecture has two modes depending on whether it can support roaming subscribers. See FIG. 1 for the LCS network architecture supporting non-roaming subscribers, and FIG. 2 for the architecture supporting roaming subscribers.
Referring to the LCS network architecture as shown in FIG. 1, a GMLC 101 allows an external LCS client 102 to make a location request for a certain mobile subscriber. If there is a location request for a certain mobile subscriber from an external LCS client, the GMLC 101 will first authenticate the mobile subscriber and make privacy verification through a privacy profile register (PPR) 103, which is connected with the GMLC via an interface Lpp 104. It then obtains via an interface Lh 105 the routing information of the mobile subscriber from a Home Location Register (HLR)/Home Subscriber Server (HSS) 106, and, forward via an interface Lg 107 the message of location request to the mobile subscriber according to the routing information of a 2nd-Generation Mobile Switching Center (2G-MSC) 108, a 2nd-Generation Serving GPRS Support Node (2G-SGSN) 109, a 3rd-Generation Servicing GPRS Support Node (3G-SGSN) 110, or a 3rd-Generation Mobile Services Switching Center Server (3G-MSC Server) 111, whichever covers the mobile subscriber at that time. The 2G-MSC 108, 2G-SGSN 109, 3G-SGSN 110, or 3G-MSC Server 111 will locate the mobile subscriber according to the received message of request for its location. The GMLC 101 will obtain the location result from the 2G-MSC 108, 2G-SGSN 109, 3G-SGSN 110, or 3G-MSC Server 111, and return it to the external LCS client 102.
The GMLC in the LCS network architecture as shown in FIG. 2 includes two parts, a Home Gateway Mobile Location Center (HGMLC) 201 and a Visiting Gateway Mobile Location Center (VGMLC) 207. The HGMLC 201 is the GMLC residing in the target mobile's home PLMN, which is responsible for the control of privacy checking of the target mobile in the 3GPP network. The VGMLC 207 is for storing the location information of the roaming mobile subscribers. The HGMLC 201 allows an external LCS client 202 to make a location request for a certain mobile subscriber. If an external LCS client makes a location request to the HGMLC 201 for a certain mobile subscriber, the HGMLC 201 will first authenticate the mobile subscriber and make privacy verification through a PPR 203, which is connected with the HGMLC via an interface Lpp 204. HGMLC 201 then obtains, via an interface Lh 205, the routing information of the mobile subscriber from an HLR/HSS 206, and forward the routing information of the mobile subscriber and location request for it to the VGMLC 207 which covers that mobile subscriber. The VGMLC 207 will send, according to the routing information of the mobile subscriber, via an interface Lg 208, the location request for the mobile subscriber to the 2G-MSC 209, 2G-SGSN 210, 3G-SGSN 211, or 3G-MSC Server 212, whichever covers the mobile subscriber at that time. A 2G-MSC 209, 2G-SGSN 210, 3G-SGSN 211, or 3G-MSC Server 212 will accomplish the location estimation for the mobile subscriber according to the received message of location request for it. The VGMLC 207 will obtain the location estimation result from the corresponding 2G-MSC 209, 2G-SGSN 210, 3G-SGSN 211, or 3G-MSC Server 212 and return it to the HGMLC 201, which will forward it to the external LCS client 202.
The 3GPP standardization organization also defines a simplified network architecture by which WLAN systems inter-work with 3GPP systems. Refer to FIG. 3 for this architecture. The WLAN network includes a User Equipment (UE) 301, a WLAN access network 302, and a 3GPP Authentication, Authorization and Accounting (AAA) Server 303. The WLAN access network is connected with the UE 301, the 3GPP AAA Server 303, and an external Internet/Intranet 304, respectively. The WLAN access network 302 interworks with an IP layer of the 3GPP network via the 3GPP AAA Server 303. The 3GPP AAA Server 303 conducts access control on the mobile subscribers while an HLR 305 or HSS 306 provides the mobile subscriber's profile and security information, an On-line Charging System (OCS) 307 provides the function of on-line charging, a Charging Gateway/Charging Collection Function (CGw/CCF) 308 provides the function of off-line charging, and a Packet Data Gateway 309 bears the data of the WLAN.
In accordance with the provisions in 3GPP TS22.934 on the inter-working of Packet Switching (PS) domain service, WLAN subscribers accessing a 3GPP network are permitted to apply for PS domain service, which includes LCS service. In another patent application of the present assignee, a subscriber-location system and method thereof applicable to WLANs have been given. The subject application puts forward a location system in a WLAN and the solution to locating WLAN subscribers in the WLAN. To be specific, a location subsystem is preset in the WLAN and this subsystem will detect, verify, store, and convert the WLAN subscribers' location information. The location information of each WLAN subscriber is provided by its access point in the WLAN, with the identification of access point used as the location information of the WLAN subscriber. Based on the said application, a subscriber can be located in the WLAN. When a client is requesting for the location information of a certain WLAN subscriber, this location subsystem will provide the appropriate location information.
Although it is possible for the current WLANs to locate its subscribers, when a certain network entity in the 3GPP network needs to obtain the location information of WLAN subscribers, it is not possible for external LCS clients to use the LCS service in the WLAN through the 3GPP network inter-working with the WLAN. This is because the 3GPP standardization organization does not provide the connection and interface standards between GMLC and WLAN. That is to say, current 3GPP provide LCS only for GSM and UMTS but not for locating WLAN subscribers, which makes it impossible for a 3GPP network to interact with the location system in the WLAN.